Casting of e.g. concrete pipes generally takes place in mould systems of the above-mentioned type by filling fresh concrete from above down into the ring gap between the vertically positioned mould parts, the concrete being then vibration compressed, while the two mould parts are displaced with respect to each other. The simultaneously rotating distributor wheel on the top of the inner mould part is to serve to distribute the concrete uniformly and evenly in the ring gap, but since the relatively dry concrete, which is normally used for such purposes, is stiff and difficult to deform in a fresh non-vibrated state, it has not been possible to distribute the concrete fully satisfactorily in the ring gap with the known distributor wheels. This problem is particularly pronounced at the upper termination of the pipe and has significantly contributed to the impossibility of casting pipes with the desired narrow length tolerances and with spigot ends which satisfy the requirements made of the quality of the concrete in any respect.